Variantly: "and just shall there be unto you": From here it was ruled: The wholesaler should clean the vessels once in thirty days, and the private person, once a year, (so that past adhesions not falsify the weight.) R. Shimon b. Gamliel says: Just the opposite. A shopkeeper cleans his measure twice a week (For a shopkeeper is not required to "drip" three drops as a wholesaler and a homemaker are, and residue remains in the vessel and sticks to it), and he wipes his weights (i.e., he cleans the stones of his scales with which he measures wet things) once a week. And he cleans his scales for every weighing.